The present invention generally relates to the study of multiphase fluid flows in porous media, specially related to methods associated with enhanced oil recovery. Enhanced oil recovery (EOR) or tertiary recovery generally targets recovery of immobile oil. EOR processes are used for recovering oil beyond secondary methods of oil recovery. EOR methods can be broadly classified into: a) thermal methods; b) gas injection methods; and c) chemical injection methods. Reservoir core plugs and outcrop core plugs are studied to investigate reservoir rock properties and mechanisms associated with water and gas based enhanced oil recovery.
Heavy hydrocarbons in the form of petroleum deposits and oil reservoirs are distributed worldwide. These oil reservoirs are measured in the hundreds of billions of recoverable barrels. The challenge to meet the ever increasing demand for oil includes increasing crude oil recovery from heavy oil reservoirs. This challenge has resulted in expanding efforts to develop alternative cost efficient oil recovery processes. Because heavy crude oil has a relatively high viscosity, it is essentially immobile and cannot be easily recovered by conventional primary and secondary means. Also, unconventional reservoir such as carbonated ones with fracture face to hardship experimental work and need to simulate unique mechanisms and conditions associated with them. Hence, there is a need in the art for new and improved means for tertiary recovery or enhanced oil recovery.
Oil is found in subterranean formations or reservoirs in which it has accumulated, and recovery is initially accomplished by pumping or permitting the oil to flow to the surface of the earth through wells drilled into the oil-bearing stratum. In the primary oil recovery stage, the recovery efficiency (RE) is influenced by the natural energy or drive mechanisms present, such as water drive, gas cap drive, gravity drainage, liquid expansion, relative permeability of reservoir formation, and combinations thereof within the formation and this natural energy is utilized to recover petroleum. In this primary phase of oil recovery, the oil reservoir natural energy drives the oil through the pore network toward the producing wells. When the natural energy source is depleted or in the instance of those formations which do not originally contain sufficient natural energy to permit primary recovery operations, some form of supplemental or artificial drive energy must be added to the reservoir to continue RE. Supplemental recovery is frequently referred to as secondary recovery, although in fact it may be primary, secondary or tertiary in sequence of employment. Enhanced recovery usually encompasses waterflooding or gas injection with or without additives, and other processes involving fluid or energy injection whether for secondary or tertiary oil recovery such as the use of steam or heated water.
Secondary recovery is a term utilized to mean any enhanced recovery first undertaken in any particular underground formation. Usually it follows primary recovery but can be conducted concurrently therewith to expedite production. Waterflooding is the most common method of secondary recovery.
Tertiary recovery refers to any enhanced recovery undertaken following secondary recovery. Broadly, tertiary recovery encompasses such procedures as miscible displacement, thermal recovery, or chemical flooding.
All of these procedures have been and, as noted, are being utilized to try to recover as much oil as possible from any given formation, but none is completely satisfactory. Many are expensive procedures not only in terms of equipment to be able to enhance the recovery, but also in terms of the chemicals and techniques utilized.
Significant challenges are associated with the recovery of hydrocarbon-containing substances such as crude oil from subterranean reservoirs. Subterranean reservoirs typically possess convoluted, fractured and crevassed bottom surface topographies wherein significant quantities of crude oil remain in locations that are inaccessible by conventional oil well extraction systems. Numerous strategies and technologies have been developed to increase the efficiency and extent of crude oil recovery from subterranean reservoirs. Such strategies include injecting water or steam or inert gas through well casings into the reservoirs to break up obstacles impeding the flow of crude oil to the well, or alternatively, to reduce the viscosity of the oil to increase its flowability.
Other strategies to increase the flowability of crude oil within subterranean reservoirs include applications of vibrational energies generated by: (a) seismic shock as a resulted of repeatedly dropping and raising a weight within a well casing, or (b) by lowering an ultrasonic wave generating device e.g., a transducer into a well casing and then manipulating the amplitude and frequency of the waves generated. However, significant volumes of crude oil remain inaccessible.
Dynamics of porous media is of intense research interest in petroleum engineering, geophysics, geotechnical engineering, water and pollution studies, and civil engineering. Demands from soil mechanics, oil production, modern earthquake and offshore engineering have further motivated the research on the dynamics of fluid-saturated porous media. Therefore, there exists a need in the art for improved methods for the design and fabrication of porous media for use in enhanced oil recovery.